The proposed postdoctoral NRSA incorporates a comprehensive research and training plan for the study of protein trafficking and cilia function in the olfactory system. Cilia are evolutionarily conserved organelles that play important roles in both sensing external stimuli and maintaining cellular homeostasis. Ciliopathies are an emerging class of human genetic disorders in which cilia function is disrupted leading to a wide variety of tissue defects. Ciliopathies in human patients can be caused by point mutations or entire deletions of cilia related genes. One of the systems that are affected by these ciliopathies is the olfactory system, leading to a reduction or loss in the ability to smell. Individual olfactory sensory neurons (OSNs) contain over 20 cilia that project into the olfactory mucosa and are responsible for detecting odorants. Since olfactory cilia lack protein synthesis components, olfactory signaling proteins must be correctly targeted to and moved throughout the cilia by specific mechanisms. It is well established that proteins move throughout cilia by the process of Intraflagellar Transport (IFT). The role of IFT in olfactory cilia development, maintenance and function is largely unknown. Aim 1 of this proposal will use a mutant mouse strain, ORPK, in which cilia maintenance and function is altered. ORPK mice are unable to detect odorants as the olfactory cilia are largely absent. Using adenovirus, I will deliver a function copy of the mutated gene, IFT88, to OSNs in order to restore olfactory cilia and importantly olfactory function. Additionally this aim will concentrate on ways to improve gene delivery to OSNs, including the use of non-viral methods. Aim 2 will investigate cilia development and olfactory function in an olfactory specific IFT88 knockout. Both mutations and deletions underlie ciliopathies; however there may be differences in the phenotypes caused by these changes. In aim 2 I will investigate changes in olfactory ciliogenesis in the olfactory specific knockout as well as testing olfactory function. Finally I will test whether adenoviral gene delivery methods can restore defects caused by IFT88 deletion. The results from these studies will provide new insight into the roles of IFT in olfactory cilia development and maintenance. Importantly the results from this project will help in the development of therapies for patients with olfactory ciliopathies, and potential therapies for other types of olfactory dysfunction as well other organ systems affected by ciliopathies.